Wanamaker, soon to appear in one of ITV’s final Poirot films, said: “It’s difficult to get work as I age, but it is always thus.

“Even Shakespeare stopped writing about women while his men aged. The young look nicer, but older women are more interesting with more to offer and better stories to tell.”

She said that acting is not the only profession affected in this way.

She added: “It’s similar in politics: there aren’t many women because they find the fighting a bit galling and give up. It’s a man’s club and that must be difficult.”

The star hopes that the number of roles for older women will gradually increase, adding: “I hope it will change because women's voices are very important and they are – sweeping generalisation – better at judging people as human beings.”

Other actresses who have also complained about sexism in the industry when it comes to female lead roles include Julie Walters, Helen Mirren and Samantha Bond.

Last month Juliet Stevenson, who stars in BBC1’s new fantasy drama Atlantis, said she considered herself “very lucky” to have landed the role at the age of 56.

“There are thousands of others between the ages of 45 and 65 who are not working because there is nothing left for them to do.”

Wanamaker admits to being annoyed with her own mother, Canadian actress Charlotte Holland, for quitting to bring up her three daughters. “She virtually gave up acting to raise us – which I’m very cross with her about,” she told the Radio Times.